01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Pelvic inflammatory disease is a polymicrobial ascending infection of the upper genital tract. Chlamydia and gonorrhoea are important, while vaginal anaerobes and other organisms explain the need for broad treatment.
No single history, examination, swab, marker or ultrasound excludes mild disease. Because delay increases infertility and ectopic pregnancy risk, compatible pelvic tenderness usually justifies empirical therapy after emergencies are assessed.
Tubo-ovarian abscess, pregnancy, sepsis, vomiting or diagnostic uncertainty warrants inpatient gynaecology care and intravenous treatment. Source control may be needed when a collection persists.
An intrauterine device does not usually require immediate removal. Review it with sexual-health or gynaecology guidance if there is no clinical improvement, balancing contraceptive needs and the timing of any removal.
Reproductive consequences should be explained without blame: even mild or unrecognised disease can scar tubes, while prompt complete treatment, partner care and prevention of reinfection reduce avoidable future harm.
Key points
- Pelvic inflammatory disease is ascending infection and inflammation of the endometrium, fallopian tubes, ovaries and adjacent peritoneum.
- Maintain a low threshold for empirical treatment with pelvic pain and cervical-motion, uterine or adnexal tenderness after important alternatives are assessed.
- A negative cervical chlamydia or gonorrhoea test does not exclude upper-genital-tract infection.
- Perform a pregnancy test in every person who could be pregnant and urgently exclude ectopic pregnancy when positive or suspected.
- BASHH outpatient treatment is ceftriaxone 1 g intramuscularly once plus doxycycline 100 mg twice daily and metronidazole 400 mg twice daily for 14 days.
- Admit for severe illness, pregnancy, tubo-ovarian abscess, inability to take oral medicine, uncertain surgical diagnosis or inadequate outpatient response.
- Arrange chlamydia and gonorrhoea NAAT, full STI testing, partner notification and abstinence until treatment and partner management are complete.
- Review within 72 hours; lack of improvement requires ultrasound, reconsideration of appendicitis or ectopic pregnancy and possible drainage.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Chlamydia and gonorrhoea
Chlamydia trachomatis and Neisseria gonorrhoeae ascend from the endocervix and are important sexually transmitted triggers of upper-genital-tract inflammation.
Polymicrobial vaginal flora
Anaerobes, Gardnerella and other vaginal organisms participate in many cases, explaining broad treatment even when STI tests are negative.
Procedure-associated ascent
Uterine instrumentation, pregnancy events and intrauterine-device insertion can transiently facilitate ascent, although ongoing risk mainly follows infection exposure.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Ascending endometritis
Organisms cross the cervical barrier, infect endometrium and spread through fallopian tubes to ovaries and pelvic peritoneum.
- 2Tubal inflammatory scarring
Neutrophilic injury and fibrosis damage cilia and narrow the lumen, impairing ovum transport and increasing infertility and ectopic pregnancy.
- 3Abscess formation
Enclosed purulent inflammation involving tube and ovary produces a complex adnexal mass that can rupture or sustain sepsis.
- 4Perihepatic inflammation
Inflammation extending along peritoneal surfaces reaches the liver capsule, producing pleuritic right upper-quadrant pain and adhesions.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Bilateral lower abdominal pain with cervical motion, uterine or adnexal tenderness supports clinical diagnosis after pregnancy emergencies are assessed.
Abnormal discharge, contact bleeding, intermenstrual or postcoital bleeding and cervical friability strengthens an ascending infection diagnosis.
High fever, vomiting, marked focal adnexal tenderness, pelvic mass or peritonism suggests severe disease or tubo-ovarian abscess.
Amenorrhoea, positive pregnancy test, unilateral pain, bleeding, shoulder-tip pain or syncope requires immediate ectopic pregnancy assessment.
Pleuritic right upper-quadrant pain with pelvic infection can represent perihepatitis, but gallbladder, liver and pulmonary causes remain important.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Pregnancy testFirst step - Why
- Identify ectopic pregnancy risk and alter antimicrobial and admission decisions.
- Interpretation and limitations
- A positive result with pelvic pain requires urgent early-pregnancy assessment; serum hCG may be needed if urine timing is unreliable.
- 02
Pelvic and speculum examination - Why
- Assess cervical motion, uterine and adnexal tenderness, discharge, bleeding and another genital cause.
- Interpretation and limitations
- Tenderness supports empirical treatment but is not specific. Avoid delaying analgesia or urgent imaging in severe pain or instability.
- 03
Chlamydia and gonorrhoea NAAT - Why
- Identify important sexually transmitted causes and guide partner management.
- Interpretation and limitations
- Collect vaginal or cervical samples and exposed extragenital sites. A negative lower-tract result does not exclude pelvic inflammatory disease.
- 04
Gonococcal culture - Why
- Provide susceptibility when gonorrhoea is suspected or NAAT is positive.
- Interpretation and limitations
- Collect before ceftriaxone where feasible, but do not postpone treatment; arrange test of cure according to guidance.
- 05
Full blood count, CRP and blood cultures - Why
- Assess severe systemic inflammation and bacteraemia when fever or admission is present.
- Interpretation and limitations
- Normal inflammatory markers do not exclude mild PID. Blood cultures are most useful in sepsis, high fever or immune compromise.
- 06
Transvaginal ultrasound - Why
- Assess tubo-ovarian abscess, pyosalpinx, ectopic pregnancy and another pelvic diagnosis.
- Interpretation and limitations
- A normal scan does not exclude uncomplicated PID; use urgently for pregnancy, mass, severe focal pain or treatment failure.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Ectopic pregnancy
Pregnancy with unilateral pain, bleeding, syncope or shoulder-tip pain requires immediate hCG and ultrasound assessment because rupture is life-threatening.
Appendicitis
Migratory or right iliac-fossa pain, gastrointestinal symptoms and focal peritonism can overlap and may require surgical review.
Ovarian torsion or cyst
Abrupt severe unilateral pain, vomiting or an adnexal mass suggests torsion, haemorrhage or rupture requiring urgent gynaecology.
Endometriosis or bladder disease
Cyclical chronic pelvic pain, dyspareunia, urinary frequency or negative infection tests may indicate non-infective gynaecological or urinary pathology.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01OUTPATIENTTreat clinically without delayFirst stepPelvic inflammatory disease is likely, the patient is stable and no admission criterion or surgical emergency is present.+
- 1Perform pregnancy testing, pelvic assessment and STI sampling, but do not await results when the clinical treatment threshold is met.
- 2Give ceftriaxone 1 g intramuscularly once plus doxycycline 100 mg twice daily and metronidazole 400 mg twice daily for 14 days.
- 3Explain adherence, adverse effects, abstinence, partner notification and emergency features and arrange sexual-health follow-up.
- 4EscalationReview response within 72 hours; escalate for worsening pain, fever, vomiting, syncope or inability to take treatment.
02ADMITManage severe or complicated diseasePregnancy, sepsis, tubo-ovarian abscess, vomiting, diagnostic uncertainty or inadequate outpatient response is present.+
- 1Involve gynaecology, use ABCDE, obtain cultures and pregnancy-related tests and arrange urgent transvaginal or other appropriate imaging.
- 2Start ceftriaxone 2 g intravenously daily plus doxycycline 100 mg twice daily, then complete 14 days with doxycycline and metronidazole after improvement.
- 3Discuss source control for tubo-ovarian abscess, rupture concern or persistent fever, considering image-guided drainage or surgery.
- 4Review thromboprophylaxis, analgesia, hydration, safeguarding, contraception and pregnancy implications during inpatient care.
03CONTACTSPrevent reinfection and sequelaePelvic inflammatory disease is diagnosed or treated empirically as a sexually associated syndrome.+
- 1Arrange testing for chlamydia, gonorrhoea, HIV and syphilis and obtain gonococcal culture where indicated.
- 2Notify and assess recent sexual partners through sexual-health services and provide epidemiological treatment according to the suspected organism.
- 3Advise no sexual contact until the patient and partners have completed treatment and the required interval is satisfied.
- 4Offer retesting, contraception and reproductive-health counselling and investigate persistent pain or fertility concerns.
04REASSESSEscalate treatment failureEscalationPain, fever or pelvic tenderness has not clearly improved within 72 hours.+
- 1Repeat examination, pregnancy assessment and observations and reconsider ectopic pregnancy, appendicitis, torsion and another surgical diagnosis.
- 2Review adherence and microbiology and arrange transvaginal ultrasound for abscess or pyosalpinx.
- 3Involve gynaecology for inpatient therapy and image-guided or operative source control when a collection is present.
- 4Document partner, abstinence, test-of-cure and reproductive-health follow-up before completing care.
Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
Ceftriaxone, doxycycline and metronidazole
Give ceftriaxone 1 g intramuscularly once, doxycycline 100 mg orally twice daily for 14 days and metronidazole 400 mg orally twice daily for 14 days.Check severe beta-lactam allergy and pregnancy, counsel about doxycycline oesophagitis and photosensitivity, metronidazole alcohol and warfarin interaction, and complete every component.
Ceftriaxone plus doxycycline inpatient regimen
Give ceftriaxone 2 g intravenously once daily plus doxycycline 100 mg orally or intravenously twice daily until improvement, then complete 14 days with doxycycline and metronidazole.Use specialist guidance in pregnancy or severe allergy, review renal and hepatic function and ensure anaerobic cover with metronidazole during oral completion.
Clindamycin plus gentamicin alternative
Give clindamycin 900 mg intravenously three times daily plus gentamicin using the local weight-based intravenous protocol, then step down with specialist guidance.Obtain specialist advice; monitor renal function and gentamicin levels, assess hearing risk, watch for Clostridioides difficile diarrhoea and select appropriate oral completion.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Tubo-ovarian abscess
Suppuration forms an adnexal collection causing persistent fever, focal pain and risk of rupture, sepsis and drainage need.
Tubal-factor infertility
Inflammatory destruction and scarring impair fallopian transport, with risk increasing after delayed treatment and recurrent episodes.
Ectopic pregnancy
Damaged tubal cilia and narrowing delay embryo transport and raise the probability of future extrauterine implantation.
Chronic pelvic pain
Adhesions, persistent inflammation and neuropathic sensitisation can cause substantial long-term pain and dyspareunia after microbiological cure.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Review within 72 hours and document improvement in pain, tenderness, fever, vomiting and oral intake.
- Review pregnancy, NAAT, gonococcal culture and STI results promptly and adjust partner management and test-of-cure plans.
- For admitted disease monitor observations, inflammatory markers, renal function and abscess drainage response according to severity.
- Advise urgent reassessment for syncope, shoulder-tip pain, increasing unilateral pain, peritonism, fever or vomiting.
- Refer persistent pelvic pain, infertility concern, dyspareunia or recurrence to gynaecology or sexual health rather than repeating antibiotics.
- Record contraception, last menstrual period, pregnancy result, safeguarding concerns and whether emergency contraception or blood-borne-virus prevention advice is required.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
A negative swab does not exclude
Upper-tract inflammation can persist after cervical organisms clear, and polymicrobial PID may occur without chlamydia or gonorrhoea detection.
Tenderness sets a low threshold
Empirical treatment is justified by compatible pelvic pain and cervical, uterine or adnexal tenderness once dangerous alternatives are addressed.
Pregnancy changes the pathway
PID is uncommon but possible in pregnancy, while ectopic pregnancy is dangerous enough to exclude urgently.
Anaerobic cover is intentional
Metronidazole addresses vaginal anaerobes and is not an optional addition to the standard outpatient regimen.
Abscess needs source control
Persistent fever or a large tubo-ovarian collection may not resolve with antibiotics alone and requires drainage or surgery discussion.
The IUD decision is reviewed
Routine immediate removal is unnecessary, but lack of improvement should prompt specialist review of removal timing alongside uninterrupted contraception planning.
Prevention continues after antibiotics
Condom advice, partner treatment, retesting and accessible sexual-health follow-up reduce reinfection that could compound tubal injury.
11Common pitfallsFrequent interpretation and management errors.
- 01
Do not wait for NAAT results before treating clinically likely pelvic inflammatory disease.
- 02
Do not exclude PID because ultrasound is normal or cervical STI tests are negative.
- 03
Do not forget a pregnancy test or allow a PID label to delay ectopic pregnancy assessment.
- 04
Do not omit metronidazole or partner management without a documented reason.
- 05
Do not discharge severe disease, tubo-ovarian abscess, pregnancy or persistent vomiting to routine oral follow-up.